JP2008083643A - Toner for electrostatic charge image development, toner cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development, the toner maintaining desired UV absorptivity over a long period of time. <P>SOLUTION: The toner contains at least one of substituted hydroxybenzoic acid, unsubstituted hydroxybenzoic acid ester and substituted hydroxybenzoic acid ester. The hydroxybenzoic acid is preferably salicylic acid, and is particularly, preferably salicylsalicylic acid. It is preferable that the toner by used concurrently as an invisible toner by using a near IR ray absorbent. The GSDv (volume average grain size distribution index) of the toner is, preferably, not larger than 1.24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner for developing an electrostatic image (hereinafter sometimes referred to as “electrophotographic toner” or simply “toner”) used in a copying machine, a printer, and the like, a manufacturing method thereof, a toner set, and an electrostatic charge. The present invention relates to an image developer and an image forming method.

  A method of creating image information through an electrostatic charge image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image is formed on a photoreceptor by a charging and exposure process (latent image forming process), the electrostatic latent image is developed with a developer containing toner (developing process), a transfer process, It is visualized through the fixing process. The developer used here includes a two-component developer composed of a toner and a carrier and a one-component developer using a magnetic toner or a non-magnetic toner alone. The toner is usually produced by a thermoplastic resin. A kneading and pulverizing method is used in which a binder resin such as a pigment is melt-kneaded with a colorant such as a pigment, a charge control agent, a release agent such as wax, and the like, cooled, finely pulverized, and further classified. To the toner particles obtained in this manner, if necessary, inorganic and organic fine particles for improving fluidity and cleaning properties may be added to the surface of the toner particles.

  In addition, as a method for producing an electrostatic image developing toner, various chemical toner production methods such as a suspension polymerization method and a dissolution suspension method have been developed, including a toner by an emulsion polymerization aggregation method, instead of the conventional kneading and pulverization method. It has been implemented. For example, in the emulsion polymerization aggregation method, a resin dispersion formed by emulsion polymerization of a polymerizable monomer of a binder resin and a fine particle dispersion such as a colorant and a release agent are mixed with an aqueous solvent in the presence of a surfactant. The toner particles, which are colored resin particles having a predetermined particle size, particle size, shape, and structure, are produced by agglomeration and heat fusion while stirring and mixing.

  In recent years, color electrophotography has been remarkably widespread, but the fields used with it have become widespread. For example, invisible information that embeds additional data by embedding additional information in an image and uses it for copyright protection of digital works such as still images, prevention of unauthorized copying, ID cards, etc. to improve counterfeiting and security Toner (invisible toner).

  Especially in recent years, copying of banknotes, family register abstracts, contracts, etc. using them has become easier due to the high performance of copying machines and printers, and illegal copying and unauthorized use have become a problem.

  The invisible information toner used for the purpose of preventing such unauthorized copying is a toner that absorbs in the ultraviolet region or near infrared region but does not absorb in the visible region. Information can be read with near infrared light. Therefore, it is possible to form an image of a bar code or an arbitrary code using the toner, embed information such as personal / company information, voice, etc., and read the information with a scanner or the like.

  Such invisible information toners have different spectral characteristics from normal cyan, magenta, yellow, and black toners that have no visible absorption (or almost no absorption) and any near-infrared absorption. There will be no specially structured material.

  However, when the above materials are used, they often have a complicated structure. For example, materials satisfying the invisible information toner include naphthalocyanine-based materials with various central metals and substituents, cyanine. Materials, croconium materials, and the like. Such materials are likely to be less stable against light and heat. Therefore, in order to prevent a reduction in light stability, an ultraviolet absorber may be used in the toner. However, when UV absorbers are contained in the toner, the photodegradation is certainly slowed down, but the UV absorbers are simply added, so that the UV absorbers are deposited on the toner image surface over time. As a result, an offset occurs, image deterioration is likely to occur, and information reading becomes difficult.

  For example, Japanese Unexamined Patent Publication No. 2000-147824 discloses a toner containing a near-infrared absorber and an ultraviolet absorber. A near-infrared absorber with high invisibility such as a naphthalocyanine-based material is simply made to contain an ultraviolet absorber.

  In this case, as described above, the ultraviolet absorber is likely to be deposited on the toner image surface over time. In particular, when prepared by the kneading and pulverizing method, the ultraviolet absorber may be present on the toner surface, and the ultraviolet absorber may be easily deposited. Depending on the type of the ultraviolet absorber, the toner such as chargeability and powder characteristics may be used. The characteristics may be reduced.

  Patent Documents 1 and 2 describe toners with improved light resistance of dyes.

Japanese Patent Laid-Open No. 7-20651 JP 2004-77707 A

  The present invention provides a toner for developing an electrostatic image that maintains a desired ultraviolet absorbing ability for a long period of time.

  Another object of the present invention is to provide a toner for developing an electrostatic charge image with a small offset even when an ultraviolet absorber is contained in the toner.

  Still another object of the present invention is to provide a near-infrared absorbing toner for electrophotography in which there is little bleeding of the ultraviolet absorber with time and offset hardly occurs.

  The configuration of the present invention is as follows.

  (1) An electrostatic latent image developing toner containing at least one of a substituted hydroxybenzoic acid, an unsubstituted hydroxybenzoic acid ester, or a substituted hydroxybenzoic acid ester.

  (2) A toner for developing an electrostatic latent image, comprising at least one of substituted salicylic acid, unsubstituted salicylic acid ester, and substituted salicylic acid ester.

  (3) The electrostatic latent image developing toner according to the above (1) or (2), further comprising a near infrared absorber.

  (4) The electrostatic latent image developing toner according to any one of (1) to (3), wherein GSDv is 1.24 or less.

  (5) A toner cartridge comprising: the electrostatic latent image developing toner according to any one of (1) to (4) above; and a toner container containing the electrostatic latent image developing toner.

  (6) A latent image forming means for forming an electrostatic latent image on the surface of the latent image holding member and a developer carried on the developer carrying member are used to obtain an electrostatic latent image formed on the surface of the latent image holding member. Development means for developing and forming a toner image, transfer means for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target, and heat fixing the toner image transferred to the surface of the transfer target 5. An image forming apparatus comprising: a fixing unit configured to perform fixing, wherein the developer includes the electrostatic latent image developing toner according to claim 1.

  It is possible to provide a toner for developing an electrostatic image that maintains a desired ultraviolet absorbing ability over a long period of time.

  Embodiments of the present invention will be described below.

  The toner of the present invention is a toner containing at least one of a substituted hydroxybenzoic acid, an unsubstituted hydroxybenzoic acid ester, and a substituted hydroxybenzoic acid ester. Preferably, the toner contains at least one of a substituted salicylic acid, an unsubstituted salicylic acid ester, or a substituted salicylic acid ester in which the hydroxybenzoic acid is salicylic acid (also referred to as o-hydroxybenzoic acid or 2-hydroxybenzoic acid). Moreover, you may add the desired coloring agent as needed. Each is illustrated below.

  In addition, other substituents other than the carboxyl group may be added within the same substituent or in another substituent. Examples thereof include an alkyl group, a halogen group, an aryl group, a phenyl group, an ester group, an ether group, a carbonyl group, a hydroxyl group, a nitro group, and a cyano group. The number of substituents may be any number as long as one or more substituents including a carboxyl group are added. Examples of substituted hydroxybenzoic acid, unsubstituted hydroxybenzoic acid ester, and substituted hydroxybenzoic acid ester are shown below.

  Examples of substituted hydroxybenzoic acids include 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-4-methylbenzoic acid, 2-hydroxy-5-methylbenzoic acid, 2-hydroxy-6-methylbenzoic acid, 2 Substituted salicylic acid such as -hydroxy-3-ethylbenzoic acid and 4-chloro-2-hydroxybenzoic acid, 3-hydroxy-4-methylbenzoic acid, 4-hydroxy-3-methylbenzoic acid, 5-bromo-2, Examples include 4-dihydroxybenzoic acid, 4-chloro-2-hydroxybenzoic acid, and 3,4-difluoro-2-hydroxybenzoic acid.

  Examples of unsubstituted hydroxybenzoic acid esters include unsubstituted salicylic acid esters such as salicylsalicylic acid and phenyl salicylate, phenyl 3-hydroxybenzoate (phenyl m-hydroxybenzoate), and methyl 4-hydroxybenzoate (p- Methyl hydroxybenzoate) and the like.

  Examples of substituted hydroxybenzoic acid esters include substituted salicylic acid esters such as phenyl 2-hydroxy-3-methylbenzoate and methyl 2-hydroxy-3-ethylbenzoate, phenyl 3-hydroxy-4-methylbenzoate, 4 -Propyl chloro-3-hydroxybenzoate, ethyl 2,4-dihydroxybenzoate and the like.

  These substituted hydroxybenzoic acid, unsubstituted hydroxybenzoic acid ester, and substituted hydroxybenzoic acid ester contain a hydroxyl group and a carbonyl group in common, and these substances resonate with keto enol type by absorbing UV, As a result, light energy is converted into vibration energy.

  The total content of these substituted hydroxybenzoic acid, unsubstituted hydroxybenzoic acid ester or substituted hydroxybenzoic acid ester with respect to the total weight of the toner is preferably 1 to 10% by weight. If it is less than 1% by weight, the ultraviolet absorption effect is reduced. On the other hand, if it exceeds 10% by weight, the binder resin content of the toner is relatively lowered, so that the toner fixing strength may be lowered, and the possibility of coming out on the toner surface is increased. There is.

  The toner described in the present invention is preferably a toner obtained by a wet method such as a polymerization method, rather than a dry method such as a kneading and pulverizing method. In the case of the kneading and pulverization method, the ultraviolet absorber may easily precipitate with time, and as a result, it is likely to be offset. On the other hand, in the case of a polymerized toner, since the ultraviolet absorber is aggregated together with the latex by the aggregating agent when the toner is aggregated, the ultraviolet absorber is less likely to be precipitated. In the agglomerated toner, it is agglomerated together with the aggregating agent and the binder resin and integrated in a form having ionic bonds, so that it is difficult for bleed to occur, UV absorption ability is maintained for a long time, and charging deterioration is suppressed. The

  In the case of salicylic acid, 3-hydroxybenzoic acid, and 4-hydroxybenzoic acid, which are unsubstituted hydroxybenzoic acids, the structure contains a hydroxyl group and a carbonyl group, but is highly hydrophilic and particularly easily soluble in hot water. Therefore, in the preparation of toner by a wet method, it is difficult to be taken into the toner, which is not preferable.

(Toner production method)
The electrostatic charge image developing toner according to the exemplary embodiment is not particularly limited for use as a toner. However, in consideration of toner characteristics, it is desirable to use the toner for invisible information pattern formation (toner for invisible information). .

  As the colorant, it is preferable to include a near-infrared absorber for use as a toner for invisible information, but there is no particular limitation in a normal case, and any material that can be used for the toner may be used. . In general, there are many colorants that are relatively less susceptible to photodegradation. For example, in the case of near-infrared absorbers used for toners for invisible information, high invisibility (= less visible absorption) and high near-infrared are used. Since absorptivity is required at the same time, the structure is often complicated, and as a result, light degradation easily occurs. In order to make the light deterioration difficult to occur, it is generally preferable to contain an ultraviolet absorber.

  The toner production method can be any of a kneading and pulverizing method, an emulsion polymerization aggregating method, a suspension polymerization method, etc., but in order to make the precipitation of the UV absorber more difficult, a coagulant is used rather than the kneading and pulverizing method. A heteroaggregation method such as the emulsion polymerization aggregation method is preferred.

  The toner production method by the emulsion polymerization aggregation method will be described in more detail. First, a resin particle dispersion in which resin fine particles are dispersed and a dispersion in which a near infrared absorber and an ultraviolet absorber are combined are mixed. Also, a dispersion of resin particles, a near-infrared absorber and aggregated particles (colorant particles) containing an ultraviolet absorber is prepared. Thereafter, the resin particles are heated and melted at a temperature equal to or higher than the glass transition point or the melting point of the resin particles to form toner particles.

  The binder resin for the toner is not particularly limited. For example, in the case of the emulsion polymerization aggregation method, a resin obtained by polymerizing a polymerizable monomer having a vinyl double bond is preferable. A styrene-acrylic copolymer resin containing an unsaturated carboxylic acid in the repeating unit is more preferable. Specifically, for example, the materials listed below can be used.

  Styrenes such as styrene and parachlorostyrene; vinyl esters such as vinyl naphthalene, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate; methyl acrylate, ethyl acrylate , N-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, etc. Acrylonitrile; Methacrylonitrile; Acrylamide; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; N-vinyl pyrrole, N-vinyl cal Tetrazole, N- vinyl indole, N- vinylpyrrolidone in N- vinyl compounds such as monomers having a free N-polar group; and the like; methacrylic acid, acrylic acid, cinnamic acid, vinyl carboxylic acids such as carboxyethyl acrylate.

  In the emulsion polymerization step, an emulsifier (dispersant) is used to make the resin into emulsified particles. Examples of emulsifiers (dispersing agents) include water-soluble polymers such as polyvinyl alcohol, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium polyacrylate, and sodium polymethacrylate, sodium dodecylbenzenesulfonate, sodium octadecylsulfate, Anionic surfactants such as sodium oleate, sodium laurate, potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, and zwitterionic surfactants such as lauryldimethylamine oxide Agent, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine Surfactants such as nonionic surfactants like, tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and inorganic compounds such as barium carbonate.

  When an inorganic compound is used as the dispersant, a commercially available product may be used as it is, but for the purpose of obtaining fine particles, a method of producing fine particles of an inorganic compound in the dispersant may be employed. As a usage-amount of a dispersing agent, it is preferable that it is the range of 0.01-20 mass parts with respect to 100 mass parts of resin (binder resin).

  In the case of the production method using the hetero-aggregation method, for example, the emulsion polymerization aggregation method usually uses a finely divided raw material of 1 μm or less as a starting material, so that in principle, a toner having a small diameter and a narrow particle size distribution can be efficiently produced. It is preferable because a high-quality fixed image can be obtained.

  The volume average particle size (median diameter) of the binder resin particles in the binder resin particle dispersion thus obtained is preferably 1 μm or less, more preferably 50 nm to 400 nm, still more preferably 70 nm to 350 nm. The range of is appropriate. In addition, the volume average particle diameter of particle | grains can be measured, for example with a laser diffraction type | formula particle size distribution measuring apparatus (the Horiba make, LA-700).

  When dispersing a near-infrared absorber or an ultraviolet absorber, as a surfactant or dispersant used for dispersion, the same dispersants that can be used when dispersing a binder resin can be used. It is better to use the same one.

  As a method for dispersing the near-infrared absorber or the ultraviolet absorber, any method, for example, a general dispersion method such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, or a dyno mill can be used. Is not to be done.

  Examples of the mold release agent used in this embodiment include, for example, low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones that exhibit a softening point upon heating; oleic acid amide, erucic acid amide, ricinoleic acid amide, stearin Fatty acid amides that show a softening point when heated, such as acid amides; plant waxes that show a softening point when heated such as carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil; Animal waxes that exhibit a softening point upon heating; mineral and petroleum waxes that exhibit a softening point upon heating, such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, microcrystalline wax, Fischer-Tropsch wax, and the like , And the like modified product. These waxes are hardly dissolved in a solvent such as toluene at room temperature or very little even if dissolved.

  Further, it is preferable to add these release agents in a range of 5 to 25% by mass with respect to the total mass of solids constituting the toner in order to ensure the releasability of the fixed image in the oilless fixing system.

  In the aggregation step in the production of the emulsion polymerization aggregation toner, aggregation can be generated by pH change to adjust the particles. At the same time, a flocculant may be added as a method for stably and rapidly agglomerating particles or obtaining agglomerated particles having a narrower particle size distribution.

  As the flocculant, a compound having a monovalent or higher charge is preferable. Specific examples of the compound having a monovalent or higher charge that can be suitably used as a flocculant include water-soluble surfactants such as the aforementioned ionic surfactants and nonionic surfactants; hydrochloric acid, sulfuric acid Acids such as nitric acid, acetic acid, oxalic acid; metal salts of inorganic acids such as magnesium chloride, sodium chloride, aluminum sulfate, calcium sulfate, ammonium sulfate, aluminum nitrate, silver nitrate, copper sulfate, sodium carbonate; sodium acetate, potassium formate, sulphate Aliphatic acids such as sodium acid, sodium phthalate, potassium salicylate, metal salts of aromatic acids: metal salts of phenols such as sodium phenolate; fats such as metal salts of amino acids, triethanolamine hydrochloride, aniline hydrochloride And inorganic acid salts of aromatic and aromatic amines.

  In consideration of the stability of the aggregated particles, the stability of the aggregating agent with respect to heat and time, and removal during washing, a metal salt of an inorganic acid is preferable in terms of performance and use. Specific examples include inorganic acid metal salts such as magnesium chloride, sodium chloride, aluminum chloride, aluminum sulfate, calcium sulfate, ammonium sulfate, aluminum nitrate, silver nitrate, copper sulfate, and sodium carbonate, but are not limited thereto.

  The amount of the flocculant added varies depending on the valence of the charge, but any of them may be small, for example, about 3% by mass or less for monovalent, about 1% by mass or less for divalent, trivalent. In this case, it is about 0.5% by mass or less. Since a smaller amount of the flocculant is preferable, a compound having a higher valence is preferable.

  In the toner manufacturing method of the present embodiment, after the fusion process is completed, the toner of the present embodiment can be obtained by proceeding to a cleaning process as necessary, followed by a solid-liquid separation process, a drying process, and the like. At this time, it is preferable that the washing step is sufficiently replaced and washed with ion-exchanged water in consideration of the chargeability. Moreover, although there is no restriction | limiting in particular in a solid-liquid separation process, From the point of productivity, suction filtration, pressure filtration, etc. are suitable. Further, the drying process is not particularly limited, but freeze drying, flash jet drying, fluidized drying, vibration fluidized drying and the like are preferably used from the viewpoint of productivity.

  The toner of the present exemplary embodiment preferably has a so-called core-shell structure in which an outer shell (shell layer) made of resin or other components is provided on the surface of main toner particles (core layer). When the toner has a core-shell structure, for example, an anthraquinone pigment is contained in the core layer, and the toner is confined in the shell layer, so that the chargeability is easily improved.

  The volume average particle diameter D50v of the toner is preferably in the range of 3 μm to 8 μm, more preferably in the range of 3.5 μm to 6 μm. When the volume average particle diameter D50v of the toner is less than 3 μm, the amount of fine powder increases, so that toner fog and poor cleaning are likely to occur. When used for invisible information toner, the information recoverability tends to be lowered. On the other hand, when the thickness exceeds 8 μm, the image quality tends to deteriorate.

  The volume average particle diameter D50v can be measured by measuring with an aperture diameter of 50 μm using a Coulter counter [TA-II] type (manufactured by Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton (trade name) aqueous solution) and dispersed by ultrasonic waves for 30 seconds.

  The volume average particle size distribution index GSDv of the toner for developing an electrostatic charge image according to this embodiment is preferably in the range of 1.0 to 1.3, and preferably in the range of 1.1 to 1.3. More preferably, it is still more preferably in the range of 1.15 to 1.24. When the GSDv exceeds 1.3, the presence of coarse particles and fine powder particles increases, so that the aggregation of the toners becomes intense, and it becomes easy to cause charging failure and transfer failure. Moreover, when GSDv is less than 1.1, it will be quite difficult to manufacture.

  In addition, the measuring method of the volume average particle diameter D50v and the volume average particle size distribution index GSDv will be described later.

  The average dispersion diameter of the near infrared absorber contained in the toner is preferably 1 μm or less, and more preferably 0.5 μm or less. When the average dispersion diameter exceeds 1 μm, the near-infrared absorptivity tends to be lowered, so that more near-infrared absorbers are required or the spectrum tends to be broad.

  The “average dispersion diameter” means the average particle diameter of individual infrared absorbers dispersed in the toner. This average dispersion diameter is determined by TEM (Transmission Electron Microscope: JEOL Datum Co., Ltd., JEM-1010) observation, for example, with respect to 1000 particulate near-infrared absorbers dispersed in the toner. The particle diameter can be calculated from the cross-sectional area of and obtained from the average value.

  The near infrared absorber used in the present embodiment is not particularly limited as long as it has absorption in the near infrared. For example, phthalocyanine compounds, aminium compounds, imonium compounds, nickel complex compounds, anthraquinone compounds, squarylium compounds, croconium compounds, polymethine compounds, naphthalocyanine compounds, merocyanine compounds, indocyanine compounds, thiocyanine compounds , Oxacyanine compounds, cyanine compounds, triarylmethane compounds, phenanthrene compounds, tetradehydrocholine compounds, croconic methine compounds, squarylium compounds, polymethine compounds, pyrylium compounds, and croconium compounds Preferably at least one compound is used.

  Further, the electrostatic charge image developing toner according to this embodiment preferably has a shape factor SF1 represented by the following formula in a range of 110 to 140, more preferably in a range of 115 to 135, and 120 to 120. More preferably, the range is 130. If SF1 is less than 110, the toner particles are close to a spherical shape, which may cause a cleaning failure after transfer. Further, if SF1 exceeds 140, transfer while maintaining image quality is likely to be difficult, and not only the infrared absorption is lowered, but also the shape range of toner particles obtained by a low temperature wet manufacturing method is exceeded. Become.

SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML represents the maximum length (μm) of toner, and A represents the projected area (μm2) of toner.

  A specific method for measuring the shape factor SF1 will be described later.

(Developer for developing electrostatic image)
The developer for developing an electrostatic charge image according to the exemplary embodiment (hereinafter sometimes abbreviated as “developer”) includes a one-component developer including the toner of the exemplary embodiment or a carrier and the toner of the exemplary embodiment. Any of two-component developers may be used. When used as a two-component developer, it is used by mixing with a carrier. Hereinafter, the case where it is a two-component developer will be described.

  There is no restriction | limiting in particular as a carrier which can be used for a two-component developer, A well-known carrier can be used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of the core material, and magnetic dispersion carriers. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  Coating resins and matrix resins used for carriers include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic. Examples thereof include, but are not limited to, acid copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenol resins, epoxy resins and the like.

  Examples of the conductive material include metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, and tin oxide, but are not limited thereto. It is not a thing.

  Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to use the carrier for the magnetic brush method, it is a magnetic material. It is preferable. The volume average particle size of the core material of the carrier is generally in the range of 10 μm to 500 μm, and preferably in the range of 30 μm to 100 μm.

  In order to coat the surface of the core material of the carrier with a resin, there may be mentioned a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be appropriately selected in consideration of the coating resin to be used, coating suitability, and the like.

  Specific resin coating methods include an immersion method in which the carrier core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed onto the surface of the carrier core material, and the carrier core material is fluidized air. And a kneader coater method in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed in a kneader coater.

  The mixing ratio (weight ratio) of the electrostatic image developing toner according to the exemplary embodiment and the carrier in the two-component developer is in the range of toner: carrier = 1: 100 to 30: 100, and 3: A range of about 100 to 20: 100 is more preferable.

(Image forming method)
Next, the image forming method of the present invention will be described. The image forming method according to the present exemplary embodiment is not particularly limited as long as the toner according to the present exemplary embodiment is used. Specifically, the following image forming method is preferable.

  The image forming method of the present invention uses a latent image forming step of forming an electrostatic latent image on the surface of the latent image holding member and a developer carried on the developer carrying member, and a static image formed on the surface of the latent image holding member. A developing process for developing the electrostatic latent image to form a toner image, a transfer process for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target, and a toner image transferred to the surface of the transfer target And a fixing step for heat fixing, wherein the developer is a developer containing at least the electrophotographic toner of the present invention. The developer may be either a one-component system or a two-component system.

  As each of the above steps, a known step in the image forming method can be used.

  As the latent image holding member, for example, an electrophotographic photosensitive member and a dielectric recording member can be used. In the case of an electrophotographic photosensitive member, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image (latent image forming step). Next, the toner particles are adhered to the electrostatic latent image in contact with or in proximity to a developing roll having a developer layer formed on the surface, thereby forming a toner image on the electrophotographic photosensitive member (developing step). The formed toner image is transferred onto the surface of a transfer medium such as paper using a corotron charger or the like (transfer process). Further, the toner image transferred to the surface of the transfer target is heat-fixed by a fixing device, and a final toner image is formed.

  FIG. 1 is a schematic diagram showing a configuration example of an image forming apparatus for forming an image by the image forming method of the present invention. The illustrated image forming apparatus 200 includes an image carrier 201, a charger 202, an image writing device 203, a rotary developing device 204, a primary transfer roll 205, a cleaning blade 206, an intermediate transfer member 207, and a plurality (three in the figure). Rolls 208, 209, and 210, a secondary transfer roll 211, and the like are provided.

  The image carrier 201 is formed in a drum shape as a whole, and has a photosensitive layer on its outer peripheral surface (drum surface). The image carrier 201 is rotatably provided in the direction of arrow C in FIG. The charger 202 charges the image carrier 201 uniformly. The image writing device 203 forms an electrostatic latent image by irradiating the image carrier 201 uniformly charged by the charger 202 with image light.

  The rotary developing device 204 includes five developing devices 204Y, 204M, 204C, and 204K that respectively accommodate yellow, magenta, cyan, and black toners. In this apparatus, since toner is used as a developer for image formation, yellow toner is used for the developing device 204Y, magenta toner is used for the developing device 204M, cyan toner is used for the developing device 204C, and cyan toner is used for the developing device 4K. Each black toner is accommodated. The rotary developing device 204 rotates and drives the five developing devices 204Y, 204M, 204C, and 204K in order so as to approach and face the image carrier 201, thereby forming an electrostatic latent image corresponding to each color with toner. To form a visible toner image and an invisible toner image.

  Here, the developing devices other than the developing device 204F in the rotary developing device 204 may be partially removed according to the required visible image. For example, a rotary developing device including four developing devices such as the developing device 204Y, the developing device 204M, and the developing device 204C may be used. Further, a developing device for forming a visible image may be used after being converted to a developing device containing a developer of a desired color such as red, blue, or green.

  The primary transfer roll 205 sandwiches the intermediate transfer member 207 with the image carrier 201 and transfers the toner image (visible toner image or invisible toner image) formed on the surface of the image carrier 201 to an endless belt-like intermediate transfer. Transfer (primary transfer) is performed on the outer peripheral surface of the body 207. The cleaning blade 206 is for cleaning (removing) the toner remaining on the surface of the image carrier 201 after the transfer. The intermediate transfer member 207 has its inner peripheral surface stretched by a plurality of support rolls 208, 209, and 210, and is supported so as to be able to rotate in the direction of arrow D and in the opposite direction. The secondary transfer roll 211 is a toner transferred to the outer peripheral surface of the intermediate transfer member 207 while sandwiching a recording sheet (image output medium) conveyed in the direction of arrow E by a sheet conveying unit (not shown) with the support roll 210. The image is transferred to a recording sheet (secondary transfer).

  The image forming apparatus 200 sequentially forms a toner image on the surface of the image carrier 201 and transfers it on the outer peripheral surface of the intermediate transfer member 207, and operates as follows. That is, first, after the image carrier 201 is rotationally driven and the surface of the image carrier 201 is uniformly charged by the charger 202, the image carrier 201 is irradiated with image light from the image writing device 203 to statically. An electrostatic latent image is formed. The electrostatic latent image is developed by the yellow developing device 204Y, and then the toner image is transferred to the outer peripheral surface of the intermediate transfer member 207 by the primary transfer roll 205. At this time, the yellow toner remaining on the surface of the image carrier 201 without being transferred onto the recording paper is cleaned by the cleaning blade 206. Further, the intermediate transfer member 207 on which the yellow toner image is formed on the outer circumferential surface temporarily moves in the direction opposite to the arrow D direction while holding the yellow toner image on the outer circumferential surface, and then moves to the next magenta. A color toner image is provided at a position where the toner image is laminated and transferred onto the yellow toner image.

  Thereafter, with respect to each color of magenta, cyan, and black, similarly to the above, charging by the charger 202, irradiation of image light by the image writing device 203, formation of toner images by the developing devices 204M, 204C, and 204K, outer periphery of the intermediate transfer member 207 The transfer of the toner image to the surface is sequentially repeated.

  Thus, a full color image (visible toner image) in which the four color toner images are superimposed is formed on the outer peripheral surface of the intermediate transfer member 207. This full-color visible toner image is collectively transferred to a recording sheet by the secondary transfer roll 211. As a result, a recorded image consisting of a full-color visible image is obtained on the image forming surface of the recording paper.

  In FIG. 1, after the toner image is transferred onto the surface of the recording paper (an example of an image output medium) by the secondary transfer roll 211, heat fixing is performed in a temperature range of 110 ° C. to 200 ° C., preferably 110 ° C. to 160 ° C. It is desirable to make it.

  Examples of the transfer target (recording material) to which the toner image is transferred include plain paper, OHP sheet, and the like used in electrophotographic copying machines, printers, and the like. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer object is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with a resin or the like, art paper for printing Etc. can be used suitably.

  The replenishment of toner used in the image forming apparatus of the present embodiment may be a replenishment of toner alone. The replenishment toner is accommodated inside, and a cartridge that can be attached to and detached from the developing unit of the image forming apparatus or its vicinity is replaced. It may be due to.

  As the cartridge, any known cartridge such as polystyrene, acrylic resin, polystyrene-acrylic copolymer, ABS resin, polycarbonate resin, polypropylene resin, polyethylene resin, polyester resin, acrylonitrile resin, or PET resin may be used. In view of strength, workability, stability, etc., more preferably, polystyrene, acrylic resin, polystyrene-acrylic copolymer, ABS resin, and polycarbonate resin are used. Moreover, you may use structural materials, such as a well-known metal material, paper, and a nonwoven fabric.

  The shape of the cartridge may be any shape such as a cylindrical shape, a column shape, a box shape, a bottle shape, a composite shape of these shapes, and other shapes. The image forming apparatus can be arbitrarily selected from the viewpoints of the internal layout, replacement / mountability, and supply toner replenishment. The arrangement of the cartridges in the image forming apparatus can be arbitrarily selected from the viewpoints of the internal layout of the image forming apparatus, exchangeability / mountability, supplyability of replenishing toner, etc. Due to the high integration of the layout accompanying the downsizing of the image forming apparatus, the cartridge shape is suitable for the cylindrical shape, the columnar shape, or the combined shape of the cylindrical shape and the box shape. But.

  In the present embodiment, the cartridge may be a replenishment cartridge containing replenishment toner inside, or a cartridge containing replenishment toner and carrier inside. Further, for example, an exchange unit that further accommodates, for example, a photosensitive drum or a developing sleeve may be used. This replacement unit may include one that is preferably used in an image forming apparatus that uses a one-component developer.

(Image forming method using invisible information toner)
In the image forming method according to the present embodiment, in the case of an invisible information pattern, only the invisible image is provided on the surface of the transfer target (image output medium), or the visible image is provided on the invisible image, and at least one of them is provided. Such an invisible image is an image forming method comprising a two-dimensional pattern, and the invisible image is formed with invisible information toner.

  The invisible image formed in the present embodiment is formed by using invisible information toner, so that the machine reading / decoding process can be stably performed over a long period of time by irradiation with infrared light, and the information can be dense. Can record. In addition, since this invisible image has no color developability in the visible range and is invisible, any image on the image forming surface can be obtained regardless of whether or not a visible image is provided on the image forming surface of the image output medium. Can be formed in the region.

  The “invisible image” is an image that can be recognized by a reading device such as a CCD in the near infrared region, and the electrostatic image developing toner that forms the invisible image has a specific wavelength in the visible light region. It means an image that cannot be visually recognized (that is, invisible) in the visible range because it has no color developability due to absorption.

The near-infrared light absorber used for the invisible information toner preferably has a maximum absorption wavelength λ _max in the range of 800 to 1000 nm, more preferably in the range of 850 to 950 nm, considering the reading wavelength. . The absorption amount of the near-infrared light absorber is such that the absorption amount at λ _max of the above wavelength is 15% or more, more preferably 20% or more.

  The “absorptivity” used here is expressed as absorptivity (%) = paper reflectivity−toner image reflectivity (%). The reflectivity is a spectrophotometer (Hitachi: U— 4000).

As a near infrared absorber, considering that the maximum absorption wavelength λ _max is in the range of 800 to 1000 nm, an aminium compound, an imonium compound, a metal complex compound, an anthraquinone compound, a squarylium compound, a cyanine compound, A croconium compound or a naphthalocyanine material is desirable. Specifically, TX-EX-910B (manufactured by Nippon Shokubai Co., Ltd.), 5, 14, 23, 32-TETRAPHHENYL-2, 3-NAPHTHALOCYANINE (hereinafter referred to as PhV (O) Nc) (manufactured by Sigma-Ardrich), ST -173 (manufactured by Sensitive Imaging Technologies Gmbh), NK-124 (manufactured by Hayashibara Biochemical Laboratories), CIR-960 (manufactured by Nippon Carlit).

  As materials other than the near-infrared light absorber used for the invisible information toner, the same materials as those for the electrostatic charge image developing toner can be used. The invisible information toner can be produced in the same manner as the toner for developing an electrostatic image by using or using a near infrared light absorbent as a colorant.

  The total amount of the near-infrared light absorbing agent in the invisible information toner is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, based on the total mass of the toner constituent solids. . If the amount is less than 0.1% by mass, absorption capable of reading information cannot be obtained. Moreover, when it exceeds 10 mass%, coloring of a near-infrared-light absorber may be conspicuous and it may become easy to recognize visually. Further, in the case of a toner used in combination with a normal colorant that can be visually observed, a near-infrared light absorber of about 0.5 to 10% by mass, preferably 1 to 8% by mass with respect to the total mass of the toner constituting solid content contains.

  The average dispersion diameter of the near-infrared light absorber in the invisible information toner is preferably 1 μm or less, more preferably 0.5 μm or less. When it exceeds 1 μm, the coloring of the near-infrared light absorber is easily noticeable.

  Since the invisible information toner absorbs in the infrared, the use of black toner using carbon black or the like causes the wavelength to overlap in the infrared region, leading to reading errors and reduced reproducibility. Toner cannot be used. Therefore, in order to achieve a black color comparable to carbon black, process black with a toner containing a mixture of three types of cyan, magenta, and yellow pigments, or a toner containing these pigments alone, a perylene compound with low near infrared absorption, It is preferable to use a toner containing an anthraquinone compound, squid ink, or the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these. Moreover, unless otherwise indicated, parts represent parts by weight.

  First, in this example, each measurement was performed as follows.

<Measuring method of particle size and particle size distribution>
The particle size (also referred to as “particle size” or “particle size”) and the particle size distribution measurement (also referred to as “particle size distribution measurement”) will be described.

  When the particle diameter to be measured was 2 μm or more, a Coulter Counter TA-II type (manufactured by Beckman-Coulter) was used as the measuring apparatus, and ISOTON-II (manufactured by Beckman-Coulter) was used as the electrolyte.

  As a measurement method, 0.5 to 50 mg of a measurement sample is added to 2 mL of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant. This was added to 100 ml of the electrolytic solution.

  The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II type with an aperture diameter of 100 μm. Volume average distribution and number average distribution were obtained. The number of particles to be measured was 50,000.

  The particle size distribution of the toner was determined by the following method. For the particle size range (channel) obtained by dividing the measured particle size distribution, draw the volume cumulative distribution from the smaller particle size, define the cumulative volume particle size to be 16% cumulative as D16v, and the cumulative volume to be 50% cumulative The particle size is defined as D50v. Further, the cumulative volume particle size that is 84% cumulative is defined as D84v.

The volume average particle diameter in the present invention is D50v, and the volume average particle size distribution index GSDv is calculated by the following equation.
GSDv = {(D84v) / (D16v)} ^0.5

  Moreover, when the particle diameter to measure was less than 2 micrometers, it measured using the laser diffraction type particle size distribution measuring apparatus (LA-700: made by Horiba, Ltd.). As a measuring method, the sample in the state of dispersion is adjusted so as to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 mL. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average particle diameter for each channel was accumulated from the smaller volume average particle diameter, and the volume average particle diameter was determined to be 50%.

  When measuring powders such as external additives, 2 g of a measurement sample is added to 50 mL of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, and 2 with an ultrasonic disperser (1,000 Hz). A sample was prepared by dispersing for a minute, and the measurement was performed in the same manner as the above dispersion.

<Method for Measuring Toner Shape Factor SF1>
The shape factor SF1 of the toner is a shape factor SF1 indicating the degree of unevenness on the toner particle surface, and was calculated by the following equation.
Formula: SF1 = (ML ² / A) × (π / 4) × 100
In the formula, ML represents the maximum length of toner particles, and A represents the projected area of the particles. The shape factor SF1 is measured by first taking an optical microscope image of the toner spread on the slide glass into an image analyzer (Luzex image analyzer: manufactured by Nireco Corporation: FT) through a video camera, and calculating SF1 for 50 toners. The average value was obtained.

<Method for measuring molecular weight and molecular weight distribution of toner and resin particles>
The molecular weight distribution is performed under the following conditions. GPC uses “HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation)” apparatus, and two columns use “TSKgel, SuperHM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15 cm)”. , THF (tetrahydrofuran) was used as an eluent. The experimental conditions were as follows: sample concentration 0.5%, flow rate 0.6 ml / min, sample injection volume 10 μL, measurement temperature 40 ° C., IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”.

<Measuring method of melting point and glass transition temperature>
The melting point and the glass transition temperature of the toner were determined by a DSC (Differential Scanning Calorimeter) measurement method, and were determined from the main maximum peak measured according to ASTM D3418-8.

  DSC-7 manufactured by Perkin Elmer Co. can be used for measurement of the main maximum peak. The temperature correction of the detection part of this apparatus uses the melting point of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. As the sample, an aluminum pan was used, an empty pan was set as a control, and the measurement was performed at a heating rate of 10 ° C./min.

<Method for measuring acid value>
About 1 g of resin is precisely weighed and dissolved in 80 mL of tetrahydrofuran. Phenolphthalein was added as an indicator, titrated with a 0.1N KOH ethanol solution, and the end point was when the color lasted for 30 seconds. From the amount of 0.1N KOH ethanol solution used, the acid value (contained in 1 g of resin) The number of mg of KOH necessary to neutralize free fatty acids was calculated according to JIS K0070: 92).

(Preparation of hydroxybenzoic acid ester particle dispersion (hereinafter also referred to as hydroxybenzoic acid dispersion) (1))
20 parts by mass of salicylsalicylic acid (manufactured by Wako Pure Chemical Industries), 1 part by mass of an anionic surfactant (Neogen R (Daiichi Kogyo Seiyaku)) and 79 parts by mass of ion-exchanged water are mixed and dissolved, and a homogenizer (manufactured by IKA, Ultrata). (Lux) was predispersed at 3000 rpm for 10 minutes, and further dispersed with a sand mill for 2 hours to obtain a hydroxybenzoic acid dispersion (1) having a volume average particle diameter D50v of 0.8 μm and a solid content concentration of 20%.

(Preparation of hydroxybenzoic acid dispersion (2))
20 parts by mass of salicylic acid (manufactured by Wako Pure Chemical Industries), 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water are mixed and prepared in the same manner as in the preparation of the hydroxybenzoic acid dispersion (1). Thus, a hydroxybenzoic acid dispersion (2) having a volume average particle diameter D50v of 0.9 μm and a solid content concentration of 20% was obtained.

(Preparation of hydroxybenzoic acid dispersion (3))
20 parts by mass of phenyl salicylate (manufactured by Wako Pure Chemical Industries, Ltd.), 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water are mixed together in the same manner as in the preparation of the hydroxybenzoic acid dispersion (1). A hydroxybenzoic acid dispersion liquid dispersion (3) having a volume average particle diameter D50v of 0.6 μm and a solid content concentration of 20% was obtained.

(Preparation of hydroxybenzoic acid dispersion (4))
20 parts by mass of 2-hydroxy-3-methylbenzoic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water are mixed to obtain a hydroxybenzoic acid dispersion liquid (1) A hydroxybenzoic acid dispersion liquid dispersion (4) having a volume average particle diameter D50v of 0.85 μm and a solid content concentration of 20% was obtained.

(Preparation of hydroxybenzoic acid dispersion (5))
20 parts by mass of 4-chloro-2-hydroxybenzoic acid (manufactured by Wako Pure Chemical Industries), 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water are mixed, and a hydroxybenzoic acid dispersion liquid (1) A hydroxybenzoic acid dispersion liquid dispersion (5) having a volume average particle diameter D50v of 0.7 μm and a solid content concentration of 20% was obtained.

(Preparation of hydroxybenzoic acid dispersion (6))
2-hydroxyethyl salicylate (manufactured by Wako Pure Chemical Industries, Ltd.) 91 parts (0.5 mole part), pyridinium dichromate 658 parts (1.75 mole part) and 2000 parts of DMF were placed in a glass container and stirred overnight at room temperature. Thereafter, filtration was performed to remove pyridinium dichromate. Thereafter, DMF was removed, and after sufficiently washing with water, 2-hydroxyethyl salicylate was obtained in a yield of 53%.

  20 parts by mass of 2-hydroxyethyl oxide of salicylic acid, 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water are mixed, and the same method as in the preparation of the hydroxybenzoic acid dispersion (1). A hydroxybenzoic acid dispersion liquid dispersion (6) having a volume average particle diameter D50v of 0.73 μm and a solid content concentration of 20% was obtained.

(Preparation of hydroxybenzoic acid dispersion (7))
20 parts by mass of 3-hydroxy-4-methylbenzoic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water were mixed to prepare a hydroxybenzoic acid dispersion (1 ) To obtain a hydroxybenzoic acid dispersion liquid dispersion (7) having a volume average particle diameter D50v of 0.8 μm and a solid content concentration of 20%.

(Preparation of near infrared absorbent particle dispersion (hereinafter also referred to as infrared absorbent dispersion) (1))
A near-infrared absorber (PhV (O) Nc) 20 parts by mass, an anionic surfactant (Neogen R) 1 part by mass, and ion-exchanged water 79 parts by mass are mixed and dissolved, and then homogenizer (manufactured by IKA, Ultra Turrax) is used. By pre-dispersing at 3000 rpm for 10 minutes and further dispersing for 2 hours with a sand mill, an infrared absorbent dispersion (1) having a volume average particle size of 0.18 μm and a solid content concentration of 20% was obtained.

(Preparation of infrared absorbent dispersion (2))
A near-infrared absorber (ST-173), 20 parts by mass, an anionic surfactant (Neogen R) 1 part by mass, and ion-exchanged water 79 parts by mass are mixed and dissolved in the same manner as the preparation of the infrared absorber dispersion (1). To obtain a dispersion liquid (2) having a volume average particle diameter of 0.20 μm and a solid content concentration of 20%.

(Preparation of infrared absorber dispersion (3))
20 parts by mass of a near infrared absorber (NK-124), 1 part by mass of an anionic surfactant (Neogen R) and 79 parts by mass of ion-exchanged water are mixed and dissolved, and the same as the preparation of the infrared absorber dispersion (1). A dispersion (3) having a volume average particle size of 0.16 μm and a solid content concentration of 20% was obtained.

(Preparation of resin particle dispersion (1))
A resin particle dispersion (also referred to as a monomer solution) was prepared by mixing and dissolving 550 parts by mass of styrene, 60 parts by mass of n-butyl acrylate, 15 parts by mass of acrylic acid, and 10 parts by mass of dodecanethiol.

  Further, 14 parts by mass of an anionic surfactant (Dow Fax, manufactured by Dow Chemical Co., Ltd.) was dissolved in 250 parts by mass of ion-exchanged water, and the monomer solution was added and dispersed and emulsified in the flask (monomer emulsion A). . Further, 1 part by mass of an anionic surfactant (Dowfax) was dissolved in 555 parts by mass of ion-exchanged water and charged into a polymerization flask. The polymerization flask was sealed, a reflux tube was installed, nitrogen was injected, and the polymerization flask was heated to 95 ° C. with a water bath while being slowly stirred. After dissolving 9 parts by mass of ammonium persulfate in 43 parts by mass of ion-exchanged water and dropping it into a polymerization flask through a metering pump over 20 minutes, the monomer emulsion is again added through a metering pump over 200 minutes. A was added dropwise. Thereafter, the polymerization flask was kept at 95 ° C. for 3 hours while continuing the stirring slowly to complete the polymerization. As a result, an anionic resin particle dispersion (1) having a volume average particle size of 200 nm, a glass transition point of 56 ° C., an acid value of 25 mgKOH / g, and a solid content of 40% was obtained.

(Preparation of release agent particle dispersion (hereinafter also referred to as release agent dispersion) (1))
46 parts by weight of paraffin wax (manufactured by Nippon Seiwa Co., Ltd., HNPO190; melting point 85 ° C.), 4 parts by weight of an anionic surfactant (Dowfax), and 200 parts by weight of ion-exchanged water are heated to 96 ° C. to homogenizer (IKA). Manufactured by Ultra Turrax T50) and dispersed at 3000 rpm for 1 hour, and then dispersed by a pressure discharge type homogenizer (Gorin homogenizer, manufactured by Gorin Co., Ltd.). A release agent dispersion liquid having a center diameter of 150 nm and a solid content of 20.0% ( 1) was obtained.

<Example 1>
(Preparation of toner particles (1))
Resin particle dispersion (1) 200 parts by mass (resin content: 80 parts by mass), Hydroxybenzoic acid dispersion (1) 50 parts by mass (particles: 10 parts by mass), Infrared absorber dispersion (1) 5 parts by mass (Particulate matter: 1 part by mass), 50 parts by mass of release agent dispersion (release agent: 10 parts by mass), 0.14 parts by mass of polyaluminum chloride are placed in a round stainless steel flask, and Ultra Turrax T50 Was mixed and dispersed at 5000 rpm for 5 minutes. Next, the flask was heated to 50 ° C. with stirring in an oil bath for heating, and held at this temperature for 60 minutes. Then, 250 parts of the resin particle dispersion (1) (100 parts by mass of resin) was added to the flask over 15 minutes. Added. Thereafter, the pH of the system was adjusted to 6.0 with a 0.5 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed and heated to 97 ° C. while continuing to stir using a magnetic seal for 5 hours. Retained.

  After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion-exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times. When the pH of the filtrate reached 7.01, No. 1 was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper. Next, vacuum drying was continued for 12 hours to obtain toner particles (1).

  When the particle diameter of the toner particles (1) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.20. Moreover, it was observed that the shape factor SF1 of the particle | grains calculated | required by the shape observation by a Luzex image analyzer is 128. Table 1 shows the characteristics of the toner particles (1).

(Preparation of developer (1))
1.2 parts of hydrophobic silica (manufactured by Cabot, TS720) was added to 50 parts of the toner particles (1), and mixed with a sample mill to obtain an externally added toner (1). Then, using a ferrite carrier having an average particle diameter of 50 μm coated with 1% by mass of polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.), the externally added toner (1) is weighed so that the toner concentration becomes 5% by mass. The developer (1) was prepared by stirring and mixing for 5 minutes in a ball mill.

<IR absorption measurement test>
For the image forming test using toner, a DocuColorCenter 500CP remodeling machine manufactured by Fuji Xerox Co., Ltd. having a structure as shown in FIG. 1 was used as the image forming apparatus. The black developer and the black toner cartridge portion of the modified machine are mounted in place of the toner developer and the toner cartridge. As a recording medium used for the image forming test, A4 size white paper (manufactured by Fuji Xerox, J-A4 paper, width: 210 mm, length: 297 mm) was used.

After each image was formed on the surface of the image output medium by the image forming apparatus using each developer, the absorption amount was calculated using a spectrophotometer (Hitachi: U-4000). The absorption amount was derived from the reflectance (R1) of λ _max at 800 to 1000 nm and the reflectance (R2) of J-A4 paper at the λ _max as shown in the following equation. The absorption amount at this time is defined as absorption amount 1.
Absorption amount (%) = R2-R1 (1)

<Light resistance test>
The medium on which the image was formed was cut out to 5 cm × 5 cm, and this was used as a light degradation acceleration test by using Suntest CPS + (manufactured by Toyo Seiki Seisakusho, light source: xenon lamp) with irradiance of 300 W / m ² , 42 degrees or less. The acceleration test was conducted in the environment. As a method for confirming the presence or absence of deterioration, the reflectance is measured using a spectrophotometer U-4000 (manufactured by Hitachi, Ltd.), the amount of absorption is calculated from the above equation (1), and the change in amount of absorption is calculated. confirmed. This absorption amount was defined as absorption amount 1, and the time when the absorption amount 1 reached 30% was defined as decomposition arrival time 1.

Further, the medium on which the image was formed was cut out to 5 cm × 5 cm, and J paper of the same size was overlaid thereon, and a weight was further placed so that a load of 80 g / cm ² was applied. It was left in the environment for 1 week. After the test, the image-formed medium was subjected to a photodegradation acceleration test as described above, and the amount of absorption and the arrival time for decomposition were similarly calculated. The absorption amount and decomposition arrival time at this time are defined as absorption amount 2 and decomposition arrival time 2. The above toner evaluation results are shown in Table 2.

<Example 2>
In Example 1, the toner particles (2), the externally added toner (2), and the toner added in the same manner as in Example 1 except that the infrared absorbent dispersion (2) was used instead of the infrared absorbent dispersion (1). Developer (2) was obtained.

  When the particle diameter of the toner particles (2) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.21. Moreover, it was observed that the particle shape factor SF1 obtained from the shape observation by the Luzex image analyzer is 129. Table 1 shows the characteristics of the toner particles (2).

  Further, the same evaluation as in Example 1 was performed using the developer (2). The results are shown in Table 2.

<Example 3>
In Example 1, the toner particles (3), the externally added toner (3), and the toner added in the same manner as in Example 1 except that the infrared absorbent dispersion (3) was used instead of the infrared absorbent dispersion (1). Developer (3) was obtained.

  When the particle diameter of the toner particles (3) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.22. Further, it was observed that the particle shape factor SF1 obtained by shape observation by the Luzex image analyzer was 130. Table 1 shows the properties of the toner particles (3).

  The same evaluation as in Example 1 was performed using the developer (3). The results are shown in Table 2.

<Example 4>
In the preparation of the toner particles (1) of Example 1, the toner particles (4) and the externally added toner are the same as in Example 1 except that the toner particles are heated to 97 ° C. and the 5-hour hold is changed to 92 ° C. 3-hour hold. (4) and developer (4) were obtained.

  When the particle diameter of the toner particles (4) was measured, the volume average particle diameter D50v was 5.8 μm, and the volume average particle size distribution index GSDv was 1.24. Moreover, it was observed that the shape factor SF1 of the particle | grains calculated | required by shape observation by a Luzex image analyzer is 135. Table 1 shows the characteristics of the toner particles (4).

  Further, the same evaluation as in Example 1 was performed using the developer (4). The results are shown in Table 2.

<Example 5>
In Example 1, the toner particles (5), the externally added toner (5), and the toner added in the same manner as in Example 1 except that the addition amount of the hydroxybenzoic acid dispersion liquid (1) was changed from 50 parts by mass to 100 parts by mass. Developer (5) was obtained.

  When the particle diameter of the toner particles (5) was measured, the volume average particle diameter D50v was 5.6 μm, and the volume average particle size distribution index GSDv was 1.23. Moreover, it was observed that the particle shape factor SF1 obtained from the shape observation by the Luzex image analyzer is 129. Table 1 shows the characteristics of the toner particles (5).

  Further, the same evaluation as in Example 1 was performed using the developer (5). The results are shown in Table 2.

<Example 6>
In Example 1, toner particles (6) and externally added toner (6) were obtained in the same manner as in Example 1 except that the hydroxybenzoic acid dispersion (1) was replaced with the hydroxybenzoic acid dispersion (3). And developer (6) was obtained.

  When the particle diameter of the toner particles (6) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.21. Moreover, it was observed that the particle shape factor SF1 obtained from the shape observation by the Luzex image analyzer is 129. Table 1 shows the properties of the toner particles (6).

  The same evaluation as in Example 1 was performed using the developer (6). The results are shown in Table 2.

<Example 7>
In Example 1, the toner particles (7), the externally added toner (7) and the toner added in the same manner as in Example 1 except that the addition amount of the hydroxybenzoic acid dispersion (1) was changed from 50 parts by mass to 25 parts by mass. Developer (7) was obtained.

  When the particle diameter of the toner particles (7) was measured with a Coulter Counter TAII, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.20. Moreover, it was observed that the particle shape factor SF1 obtained from the shape observation by the Luzex image analyzer is 129. Table 1 shows the characteristics of the toner particles (7).

  Further, the same evaluation as in Example 1 was performed using the developer (7). The results are shown in Table 2.

<Example 8>
89 parts of linear polyester (linear polyester obtained from terephthalic acid / bisphenol A / ethylene oxide adduct / cyclohexanedimethanol: Tg = 62 ° C., Mn = 4,000, Mw = 35,000, acid value = 12, water Acid value = 25), 5 parts of salicylsalicylic acid, 0.5 part of PhV (O) Nc and 5 parts of polyethylene wax (melting point: 135 degrees) as a near infrared absorber are kneaded with an extruder and pulverized with a pulverizer Thereafter, the process of classifying fine particles and coarse particles with an air classifier and obtaining particles having an intermediate diameter is repeated three times to obtain toner particles (8), externally added toner (8) and developer (8). It was.

  When the particle diameter of the toner particles (8) was measured, the volume average particle diameter D50v was 9.2 μm, and the volume average particle size distribution index GSDv was 1.39. Further, the shape factor SF1 of the toner particles (8) obtained by shape observation with Luzex was 151. Table 1 shows the characteristics of the toner particles (8).

  Further, the same evaluation as in Example 1 was performed using the developer (8). The results are shown in Table 2.

<Example 9>
In Example 1, toner particles (9) and externally added toner (9) were obtained in the same manner as in Example 1 except that the hydroxybenzoic acid dispersion (1) was replaced with the hydroxybenzoic acid dispersion (4). And developer (9) was obtained.

  When the particle diameter of the toner particles (9) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.21. Further, it was observed that the particle shape factor SF1 obtained by shape observation by the Luzex image analyzer was 130. Table 1 shows the characteristics of the toner particles (9).

  Further, the same evaluation as in Example 1 was performed using the developer (9). The results are shown in Table 2.

<Example 10>
In Example 1, toner particles (10) and externally added toner (10) were obtained in the same manner as in Example 1 except that the hydroxybenzoic acid dispersion (1) was replaced with the hydroxybenzoic acid dispersion (5). And developer (10) was obtained.

  When the particle diameter of the toner particles (10) was measured, the volume average particle diameter D50v was 5.65 μm, and the volume average particle size distribution index GSDv was 1.20. Moreover, it was observed that the particle shape factor SF1 obtained from the shape observation by the Luzex image analyzer is 129. Table 1 shows the characteristics of the toner particles (10).

  Further, the same evaluation as in Example 1 was performed using the developer (10). The results are shown in Table 2.

<Example 11>
In Example 2, toner particles (11) and externally added toner (11) were obtained in the same manner as in Example 2, except that the hydroxybenzoic acid dispersion (1) was replaced with the hydroxybenzoic acid dispersion (6). And developer (11) was obtained.

  When the particle diameter of the toner particles (11) was measured, the volume average particle diameter D50v was 5.72 μm, and the volume average particle size distribution index GSDv was 1.22. Moreover, it was observed that the shape factor SF1 of the particle | grains calculated | required by the shape observation by a Luzex image analyzer is 131. Table 1 shows the characteristics of the toner particles (11).

  Further, the same evaluation as in Example 1 was performed using the developer (11). The results are shown in Table 2.

<Example 12>
In Example 2, toner particles (12) and externally added toner (12) were obtained in the same manner as in Example 2 except that the hydroxybenzoic acid dispersion liquid (1) was replaced with the hydroxybenzoic acid dispersion liquid (7). And developer (12) was obtained.

  When the particle diameter of the toner particles (12) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.20. Moreover, it was observed that the shape factor SF1 of the particle | grains calculated | required by the shape observation by a Luzex image analyzer is 128. Table 1 shows the characteristics of the toner particles (12).

  Further, the same evaluation as in Example 1 was performed using the developer (12). The results are shown in Table 2.

<Comparative Example 1>
In Example 1, toner particles (13), an externally added toner (13) and a developer (13) were obtained in the same manner as in Example 1 except that the hydroxybenzoic acid dispersion liquid (1) was not added.

  When the particle diameter of the toner particles (13) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.19. Moreover, it was observed that the shape factor SF1 of the particle | grains calculated | required by the shape observation by a Luzex image analyzer is 128. Table 1 shows the characteristics of the toner particles (13).

  Further, the same evaluation as in Example 1 was performed using the developer (13). The results are shown in Table 2.

<Comparative example 2>
In Example 1, it produced similarly to Example 1 except having replaced with the hydroxy benzoic acid dispersion liquid (1) instead of the hydroxy benzoic acid dispersion liquid (1). After the preparation, the toner dispersion was cooled to room temperature and the stirring was stopped. A white precipitate (salicylic acid) was observed at the bottom of the kettle. Similarly, toner particles (14), externally added toner (14) and developer (14) were obtained.

  When the particle diameter of the toner particles (14) was measured, the volume average particle diameter D50v was 5.7 μm, and the volume average particle size distribution index GSDv was 1.22. Moreover, it was observed that the shape factor SF1 of the particle | grains calculated | required by the shape observation by a Luzex image analyzer is potato shape with 129. Table 1 shows the characteristics of the toner particles (14).

  Further, the same evaluation as in Example 1 was performed using the developer (14). The results are shown in Table 2.

  As described above, since the electrostatic image developing toners of Examples 1 to 12 contain a material in which a substituent containing at least a carboxyl group is added to salicylic acid ester, an ultraviolet absorber is simply added to the normal toner. Rather than doing this, the offset can be significantly reduced. Therefore, even when irradiated with light, the toner image contains a large amount of a material in which a substituent containing at least a carboxyl group is added to the salicylic acid ester, so that photodegradation can be suppressed.

  The electrostatic image developing toner of the present invention is particularly useful for applications such as electrophotography and electrostatic recording.

It is the schematic which shows the structural example of the image forming apparatus for forming a visible image simultaneously with an invisible image.

Explanation of symbols

  200 Image forming apparatus, 201 Image carrier, 202 Charger, 203 Image writing apparatus, 204 Rotary developer, 204Y Yellow developer, 204M Magenta developer, 204C Sian developer, 204K Black developer, 205 Transfer Roll, 206 Cleaning blade, 207 Intermediate transfer body, 208, 209, 210 Support roll, 211 Secondary transfer roll.

Claims (6)

  A toner for developing an electrostatic latent image, comprising at least one selected from substituted hydroxybenzoic acid, unsubstituted hydroxybenzoic acid ester, and substituted hydroxybenzoic acid ester.   An electrostatic latent image developing toner comprising at least one of substituted salicylic acid, unsubstituted salicylic acid ester, and substituted salicylic acid ester.   The electrostatic latent image developing toner according to claim 1, further comprising a near infrared absorber.   4. The electrostatic latent image developing toner according to claim 1, wherein GSDv is 1.24 or less. The electrostatic latent image developing toner according to any one of claims 1 to 4,
A toner cartridge comprising a toner container for containing the electrostatic latent image developing toner. Latent image forming means for forming an electrostatic latent image on the surface of the latent image holding member;
Developing means for developing a toner image by developing the electrostatic latent image formed on the surface of the latent image holding body using the developer carried on the developer carrying body;
Transfer means for transferring the toner image formed on the surface of the latent image holding member to the surface of the transfer target;
Fixing means for thermally fixing the toner image transferred to the surface of the transfer target;
With
The image forming apparatus according to claim 1, wherein the developer includes the electrostatic latent image developing toner according to claim 1.

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